Hi! I am new here as well and am just beginning the journey of SPD with my three year old daughter. I just wanted to say that what you described about the clothing and having meltdowns if things are not "just right" is 100% my day to day experience with Lulu. I have no doubt in my mind that she has SPD and am currently filling out the paper work for an Occupational Therapy Evaluation. Hopefully they can give me some survival skills to deal with this disorder and make life a bit less painful for my girl. Everything for my girl is "too tight"- the seat belt causes constant screaming. She can not stand to wear socks, underwear, pants that aren't leggings, and will only wear one pair of shoes. She seems to take comfort in tight hugs and hand holding.
Something else you said jumped out at me. Lulu also often squeezes our animals too tight and I have to remind her constantly to give the dog "nice touches". She was very aggressive with her sister, often scratching, hitting, and hair pulling, but this seems to have calmed down a bit.
I hope that you get some help with occupational therapy and it gives you some coping skills. I am really looking forward to seeing a professional, since my knowledge right now is so limited. I just wanted you to know that you are not alone!